Ostrich Feather Structure and Quality

There are many different types of Ostrich Feathers depending on the age of the bird, the sex of the bird and where they are positioned on the bird.

Figure 1 explains the following terms and illustrates various defects that may be present in an ostrich feather. A feather consists of a Plume (the larger part of the feather) and the Quill (the naked stalk at the bottom end of the feather).  A Plume consists of a Shaft (rachis) with branched Barbs on which Barbules are found.  Every Barbule has a Base and a Pennulum, on which minute spikelets (Barbicels) are found, which are called Fila, without the normal Hooklets (Pyecraft, 1898).  These Hooklets would normally hook onto the Hooklets of adjacent barbs’ Barbules to form a network in perching birds.  The bases of the barbules of all flightless birds are twisted.  A single Barb with Barbules is called a Plumule, and all the Plumules together is the Flue.  A single Plume has a Butt (at the point closest to the base) and a Tip (at the point furthest from the base).[1]

Figure 1: Ostrich Feather Drawing illustrating definitions, terminology and and some defects (compiled from Swart, 1979)

Commercial Characteristics of Ostrich Feathers

Length
Plume length is one classification for Male Wing Feathers, Feminas and Drabs.

Breadth
Breadth is a measurable characteristic. The Plumule length should be equal on either side of the Plume and referred to as “Equal Width of the Flue”.   The plume of wing feather breadth classes varies from 1 very narrow to 5 very wide - less than 25cm, +/- 28cm, +/-32cm, +/-36cm and more than 40cm.    Also important is the Length of the Plumules, the strength of the plumules and the angle at which the plumules join the stalk.

Shape of Feather
The shape of the feather is dependent on the shape of the tip and the butt, as well as a “clean margin” with no “streamers” to ensure the clarity of definition of the flue.  The Plumules must also be blunt on the ends and the barb length equal, not breaking the margin.

Tip
Tip classes of 1 to 5 corresponds to
1.    a very narrow and sharp pointed tip
2.    an angle of 90° or less but not pointed
3.    an angle of more than 90° but not “blunt”
4.    wider point but not round
5.    a broad round point

Butt
The Butt can be:
1.    narrow and tapering to a point (gradually shortening of the barbs to the base of the plume)
2.    less narrow
3.    rounded and narrower than the rest of the plume
4.    rounded or square, but narrower than the rest of the plume
5.    square and at least as wide as the rest of the plume.

Margin
The margin (clarity of margin definition) classes are
1.    very tendril-like, untidy with lots of “streamers”
2.    tendril like, with uneven edge
3.    moderately smooth, with uneven plumule length
4.    smooth, with ragged edge
5.    very smooth, with even length of plumules, each with rounded edges

Flue Strength
Flue strength, or self-support of the flue, is divided into six classes.   It acknowledges that the flue may be too strong (hard).

1.    resembles the branches of a willow tree and is over weak (woolly)
2.    is very weak (woolly) and the plumules bend at their bases
3.    is weak (woolly) and the plumules bend downwards
4.    is string (hard) and the plumules bend at their bases, but the plumules still bend
5.    is very strong (hard) and the plumules do bend, but not downwards
6.    is too strong (hard), the plumules point upwards and no bending occurs.  For dying and manufacturing the hard plume is preferred.

Flue Density
The total density or compactness of the flue is a function of the amount of barbs per unit of length of the shaft, the amount of barbules per unit of length of the barb, the length of the barbules themselves (reflected in the width of the plumules), and probably barbule diameter.

There are 5 classes for flue density:
1.    very sparse and translucent
2.    sparse and fairly translucent
3.    moderately dense, with even cover and normal density
4.    dense, with even density flue, but slightly translucent
5.    very dense, with non-translucent dense flue.

A visual estimate of the barbs per unit of length is classed as [1] sparse, with noticeable gaps between barbs (or plumules), 2 moderate, with normal definition of barbs, and [3] dense, with barbs closely associated or even double.

Classifications of the width of the plumules:
1.    very narrow (3 – 4mm)
2.    narrow (5 – 6mm)
3.    moderately wide (7 – 8 mm)
4.    wide (9 – 10 mm)
5.    very wide (11 – 12mm).

Hand
This characteristic is a function of the length of barbules (width of plumules), texture or coarseness of barbules, elasticity or strength of the flue.

Classifications for the hand or softness of the Flue:
1.    hard, hard cotton or too strong (hard) flue
2.    stiff or strong, cotton-like and strong (hard) flue
3.    normal, elastic cotton-like, medium strong
4.    soft elastic, elastic silky (ideal class)
5.    very soft, silky hand.

Lustre
Flue lustre varies from dull 1 to bright 5.  This is largely the result of the so called “oiliness” of the flue.  Actual fat content, however, does not play any role in this characteristic, but the size and shape of the fila determines this characteristic. This characteristic is classified:

1.    no “oil”, with dry, loose barbules without elasticity (mimosa-leaf-like flue)
2.    slightly “oily”, mimosa-leaf-like
3.    moderately “oily”, elastic mimosa-leaf-like flue, with normal lustre
4.    “oily”, with elastic willow-like flue
5.    very fatty, with sticky willow-like flue.

Flue Character
The character of the flue is another characteristic evaluated subjectively and refers to the amount of disruption of the barbules in a plumule with:

1.    very bad - with prickly flue (barbules)
2.    bad - clear disruption of flue (barbules), with prickly hair (barbules)
3.    moderate - with disrupted symmetry, but no overlapping of barbules
4.    good - with good symmetry, but not perfect arrangement of barbules
5.    very good - with symmetrical or parallel arrangement of barbules

Quality
Flue Quality definitions are dependent on four correlated characteristics, namely:
1.    hand or texture
2.    lustre
3.    “oiliness”
4.    flue character.

Short thick (strength) barbules are undesirable, whole long, thin barbules (medium strength) with no disruption (silky) are preferred.  Suggestions for defining Flue “quality” are

1.    dry cotton-like, with no elasticity, dull, too strong, very hard and dry
2.    cotton-like, non-elastic, dull, strong flue, dry and hard
3.    silky cotton, moderately silky, normal lustre, medium fine to medium strong and of reasonable character
4.    silky, with normal lustre, medium fine, moderate “oiliness” and good character
5.    elastic silky, lustrous, notable “oiliness”, very good character and moderate flue strength

Damaged and Defective Feathers

Wear
The degree of wear varies from no wear [1] to extremely worn [5] and judged by examining the tips.  In contrast to all other characteristics, the lower the class the better the product is.

1.    describes no wear
2.    minimal wear, with no broken tips
3.    moderate wear with no noticeable broken tips
4.    noticeable wear
5.    noticeable broken tips (“tipless”), broken plumules and excessive wear

Soiling
The amount of soiling is judged visually with:

1.    no soiling, white feather flue
2.    minimal, not noticeably soiled
3.    moderately, noticeable, diluted soiling
4.    excessively, clearly visible soiling
5.    extremely soiled, red brown colour

Note on soiling.  Some soiling can happen during transport and time in the lairage, especially if over crowded.  It can also come from blood at time of slaughter.  It was also thought that the sandy colour that can get onto some feathers may be as a result of the soil where the birds are kept.  More recently it is accepted this maybe a genetic trait.  Only adequate data from long term records of birds and their progeny would be able to determine if this type of discolouration is genetic or staining from local soil.

Bars
Bars are the vertical lines of defects that may occur after a break in feather growth, for whatever reason, has occurred.

1.    no or very little bars
2.    very little bars,
3.    a few bars
4.    a noticeable amount of bars
5.    has a lot of bars.

Figure 2 illustrates a bar.  Note how the left side of this feather has many bars and also some severely damaged barbules, but the right side is in reasonably good condition.

Figure 2: Poor quality feather illustrating Bars

Flue Behaviour
This characteristic refers to the parallel arrangement of barbs, with overlapping judged as a negative effect.  Again there are five classes used, which are judged subjectively from class 1 with a lot of disarrangement and class 5 with no overlapping.

Flue Style
Style refers to the “cohesion” between barbs and used to group feathers into five classes ranging from very open -class 1, to uniform - class 5).

Spiral twist (plume behaviour)
Spiral twist results in a feather that has a twisted tip.  Five different classes describe spiral twist from very bad 1 to straight 5.

Plume Strength
Plume strength refers to the strength of the shaft.  Class 1 is when one third of the plume falls forward to a class 5 when no bending occurs.  In general class 4 is preferred.

Shaft Thickness
The shaft thickness has 3 classifications, fine, medium and thick.  A fine shaft is preferred, probably because it adds little to the mass of the flue.

Colour deviations
Pure and brilliant white feathers are the most desirable with degree of determining the classes, with pure white plumes defined as Class 1 and plumes with grey spots as Class 5.

Feather Types

Drabs – Body Feathers
Sold natural and dyed
Sold in different lengths.  Class lengths are usually 22 to 25cm, 15 to 20cm and 12 to 20cm.  Drabs will be taken from slaughter birds and either adult female or chick body feathers.

Blacks – Male Body Feathers sold as Drabs

Male Wings – Mature Male White Wing Feathers

Feminas – Female White Wing Feathers

Tail Feathers – Feathers from the tails of Adults and Slaughter Birds

Spadonas – (Spads) are Chick wing feathers.

Floss – Soft Body Feathers

Blondenes – Light coloured body feathers

Bycocks – Transition feathers from Body to Wing

Slopes – Poorly shaped feathers

Ruggies – 5th and 6th Quality feathers

The most common way to sell feathers is by the kilo.  However there are occasions for selling by the individual feather for those who want them for non-industrial uses or low volume.

Products

Carnivals, Shows and Fashion take the majority of adult wing feathers and the better quality chick wing feathers.  The most popular industrial use for the feathers is feather dusters.   There are a few other novelty products such as quill pens, quill pencils, fans and key rings.  For more information please visit the Ostrich Feather Products information page.

Summary

Ostrich feathers are unique with special qualities with the potential for high value.  They also represent less than 5% of the total revenue of a slaughter bird.  Harvesting feathers at any time other than after slaughter will impact on production (egg prodcution in breeder birds and growth rates and feed converstion in slaughter birds) and therefore carry a cost implication from lost production that farmers need to cost into their production costs.

All current published data on feathers indicates there is significant variabliatly in quality in feathers, which one would expect when the simalar degrees of variation are prevalent in the quality of carcasses and skins.

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[1] Practical Guide to Ostrich Farming F.D. Mellet 1995

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